1. Field of the Invention
This invention relates generally to funnels, specifically to a funnel which prevents the emission of ecologically and/or environmentally harmful vapors from its underlying container.
2. Description of Related Art
Laboratories and other facilities which use volatile chemicals, such as benzene, dichloromethane and other solvents and diluents, usually have frequent needs to dispose of quantities of such chemicals. For example, a research laboratory may use benzene, acetone, dichloromethane to clean lab ware, dichloromethane (methylene chloride) to elute an impurity from a substance in chromatographic procedures, or may generate various organic waste from performing chemical or biochemical research. Waste solvents or solvent mixtures that are not recyclable usually contain contaminants and thus must be disposed.
In a typical research and development facility, the disposal of such waste solvents are performed by disposing the solvent in a container such as a carboy that may be made of polypropylene or glass. In standard applications, the disposal of the solvent may be performed by removing the cap of a carboy or container, a funnel is inserted and left in the stem of the carboy, and the waste solvent is disposed into the carboy using the funnel. When the carboy is filled, the carboy is capped and the container is then transferred to an approved disposal, recycling, or incineration facility.
This system of disposal has several significant environmental disadvantages. Among others, the solvent present in the carboy is left exposed and open to the atmosphere because the stem funnel is not sealingly secured, the stem funnel passes through the stem of the carboy and is open to the atmosphere. Thus the volatile solvent or solvent mixtures evaporate and contaminate the local environment and atmosphere. The high rate of evaporation is further accentuated by the fact that most containers for the disposal of solvents are stored in a ventilated or fume hood, where the high air flow further increases the rate of solvent evaporation.
In a standard application, a typical 8-gallon carboy will usually be filled with waste solvents after a period of several days or weeks, and a considerable amount of solvent will evaporate to the atmosphere over the extended period of time. Even if the carboy was recapped at the end of each day, when the carboy is not in use, a considerable amount of solvent will still evaporate to the atmosphere during the workday when the cap is removed, the funnel is installed, and the patent path was present. Even with the best laboratory practice of diligently recapping the carboy at the end of each work day, even during a typical 8 hours work day, a large amount of undesirable vapor emission is produced even when a standard laboratory funnel is left on the bottle or the carboy.
While it may appear that the contamination of the atmosphere from such evaporation may not be significant, tests have shown that loss of solvents from such evaporation is quite significant. For example, in an 8-liter carboy filled with dichloromethane, 500 ml. (or about 0.663 kg) of this solvent evaporates into the atmosphere via the stem of the funnel in a period of 114 hours (4.75 days). In one study performed by Brian Bateman (Bay Area Air Quality Management District (BAAQMD), Laboratory Building Fume Hood Modeling Study, September 1994), it was demonstrated that each 25,000 square feet of a typical research laboratory space releases enough volatile organic solvents (VOCs) into its atmosphere to (statistically) cause one person per million in the San Francisco Bay Area to contract some form of cancer. In addition, the atmospheric contamination by VOCs has other well known deleterious effects, and may contribute to smog, haze, destruction of the protective ozone layer, etc . . . It has also been shown that localized pollution by VOCs contributes to asthmatic conditions and poor health, in general.
This evaporation and contamination problem and its concomitant deleterious effects can be significantly reduced by not leaving the funnels with their patent stems in carboys when the system is not in use. In order to accomplish this, however, each carboy or solvent container would have to be kept capped and sealed at all times (except during disposing of solvent). When capped in this manner, a researcher or laboratory technician would have to place the container containing the waste solvent to be disposed of on the laboratory bench, remove the cap from the carboy, insert a funnel, dispose of the waste solvent, then remove the funnel and recap the carboy each time the user needs to dispose of waste solvents. Because of the multiple steps involved in this effort to dispose of waste solvents, experience has shown that laboratory personnel will be simply not performed these arduous steps for disposing solvents through out the day. Instead the user will tend to leave the carboy open with the funnel inserted at all times during the day and over the work week, thereby contaminating the atmosphere through solvent evaporation.
In addition to the above problems, the addition of solvent to a container using a standard funnel often results in liquid pulsations or burps that may result from the differential pressure between the environment and the inside pressure of the container as increasing volume of solvent is added to the container. In addition, as solvent is added, the solvent entering the container must share the same pathway with the displaced air that is venting out of the container. One way to eliminate such pulsation or burping is by the careful transfer of solvent such that the funnel path never floods or occludes the escaping or venting air. However, this method requires a slow addition of solvent and a significant amount of operator skill that is rather difficult and unmanageable at all times, particularly when the disposal of viscous liquids are performed.
U.S. Pat. No. 5,676,185 (1997) to Starr et al discloses a vented funnel for a closed head hazardous waste container. The patent claims a drum coupling that is connected to the funnel body and does not disclose coupling mechanism for laboratory containers nor does the patent teach any methods for safely transferring solvents to prevent overfill.
Ravishankar, in U.S. Pat. No. 4,803,946 (1989), discloses a funnel with a long drain stem which extends into the liquid solvent in the collection tank below the funnel. This results in reduced buildup of solvent on the walls of the tank. However the top of the funnel is still left exposed, so that solvent can evaporate through the stem of the funnel into the atmosphere.
U.S. Pat. No. 5,033,520 to Kuehmichel (1991) discloses a large metal drum with a top funnel having an offset stem which is inserted into a bung opening in the top of the drum. Solvent can evaporate into the atmosphere via such stem, which is patent. The drum has a top cover, but this must be removed with the funnel is installed.
Offenlegungschrift DE 39 36 099 A1 to Kuehmichel (published 1991) discloses a drum with a long-stemmed funnel which extends into the liquid in the drum. This arrangement also suffers from the same disadvantages of solvent evaporation as noted above.
Europaische Patentanmeldung 0 582 126 A1 to Recycling-Chemie-Niederrhein (published 1993) shows a similar funnel and drum arrangement with the same disadvantages.
A laboratories supplies catalog from Scienceware by VWR Scientific, West Chester, Pa. (1994) shows, on pp. 18 and 38, funnels with caps which are hinged to the upper rim of the funnel. The caps can be held stably in either the open (vertically upright) or closed position. This cap will not prevent the evaporation-contamination problem because it does not form an airtight closure on the funnel. Moreover, the funnel lacks an extended stem that extends into the container beyond the neck of the container or lacks a stem that immerses into the liquid. An extended stem or a stem that is immersed into the liquid as liquid is being added to the container significantly reduces solvent evaporation, since the extended stem reduces the available vapor volume only to the volume that is present in the stem as opposed to the larger volume of the head space of the container. In addition, it has been observed that a typical user will tend to leave the cap of the container off after use, thereby losing any and all benefits for containing solvent vapors that the cap could possibly provide. It has been demonstrated that solvent containers with the presence of a larger head space leading to the opening in a particular container that is equipped with a standard funnel will provide a higher rate of solvent loss than a container with a smaller head space leading to the opening of the container.